x86: Move TS_COMPAT back to asm/thread_info.h

Move TS_COMPAT back to asm/thread_info.h, close to TS_I386_REGS_POKED.

It was moved to asm/processor.h by b9d989c7 ("x86/asm: Move the
thread_info::status field to thread_struct"), then later 37a8f7c3
("x86/asm: Move 'status' from thread_struct to thread_info") moved the
'status' field back but TS_COMPAT was forgotten.

Preparatory patch to fix the COMPAT case for get_nr_restart_syscall()

Fixes: 609c19a3 ("x86/ptrace: Stop setting TS_COMPAT in ptrace code")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210201174649.GA17880@redhat.com